Various electronic apparatuses that support social infrastructures are increased in speed according to enhancement of functions. The electronic apparatuses need to be designed such that electromagnetic noise radiated from the apparatuses does not cause electromagnetic interference with radio communication apparatuses that are expected to further increase in future. When an electromagnetic interference problem occurs, a quick survey in the site is necessary. There is a demand for an apparatus that visualizes an occurrence source of the electromagnetic noise on a real-time basis.
As a visualizing technique for an electromagnetic wave, there is Patent Literature 1 (JP-A-2009-33324). Patent Literature 1 mentions that “An antenna 1A includes an EBG 1, which is a reflection plate, and is configured by arranging an antenna element 15 in a position of height h above the EBG 1. In the EBG 1, square patches 11 formed small compared with an operating wavelength are cyclically arrayed in a matrix shape on the surface of a square substrate 10. A ground plane 13 is formed on the rear surface of the substrate 10. As the patches 11, in an example shown in the figure, twenty-five patches P1-1, P1-2, . . . , P5-4, and P5-5 in five rows×five columns are provided. Variable capacitors 12, which are variable capacity diodes, are connected among the patches. A resonance frequency of the EBG 1 is changed by controlling a value of a voltage +V applied to the patches 11 to change a capacitance value of the variable capacitors 12”.
There is also Patent Literature 2 (JP-A-2008-288770). Patent Literature 2 mentions that “ . . . includes a conductor plate 2, a plurality of metal platelets 1 having the same shape, a plurality of coupling bodies 4, and a capacitance element 6. The respective plurality of metal platelets 1 are regularly arrayed, disposed to be opposed to an upper part of the conductor plate 2, and electrically connected to the conductive plate 2 via the coupling bodies 4. The metal platelets 1 adjacent to one another are electrically connected via a plurality of the capacitance elements 6 distributedly disposed for each of the metal platelets 1 adjacent to one another”.